Hybrid Tunable Magnet Actuator: Design of a Linearized Force–Flux Tunable Magnet Actuator

Recent studies have shown that tunable magnets (soft permanent magnets) can significantly reduce Joule heating in electromagnetic actuators. To achieve high motion accuracy and repeatability, this article proposes a novel actuator design with a linearized force–flux relation. In prior designs of variable reluctance tunable magnet actuators, the force and flux are related quadratically via a C-shaped actuator. Hybrid tunable magnet actuators based on biased fluxes are developed using lumped parameter models. Using finite element analysis, it is shown that the force–flux relation is symmetric linear around the mid position depending on the magnetic flux direction in the magnet. Within a position range of
$\pm$
500
$\mu$
m and a force range of
$\pm$
20 N, the linear fit produces a negligible error of 0.08 N. Finally, this linear relationship is validated with a 0.03-N error in an experimental setup.